Many of us buy generic products. We go to the pharmacy and we ask the pharmacist to substitute the generic version of the medicine the doctor has prescribed for us. Or we go to the grocery store and we substitute Marshmallow Maties for Lucky Charms because we can get almost twice as many Marshmallow Maties for the price of Lucky Charms. Plus, let’s just be honest. Marshmallow Maties are better than Lucky Charms. Usually we don’t feel bad the substitution because there’s almost no difference between the name brand and the substitute. But of course that’s not always true.
Centuries ago when food production moved from the home to the factory, the pressures of large-scale manufacturing prompted merchants to resort to shortcuts. Cash hungry bakers discovered that they could make their dough go further if they mixed their dough with powdered alum and sulfur of copper. Dairy farmers sold cream thickened with flour, watered down their milk and at times added chalk or plaster of Paris to perk up the color of milk that came from diseased cows. Some grocers were known to make their sugar go further by mixing sand in with it.
There were merchants that would put together a collection of calcium, gypsum, gelatin fat and mashed potatoes and call it butter. There was a product that was nicknamed “bogus butter” that was made from, among other things, distilled hog fat and bleach. One of the worst food substitutions I read about occurred as recently as 1969 when a man in England was charged with selling phony grated parmesan cheese. It turns out what he was really selling was ground up umbrella handles. There are times when substitutes can be as good as the original, but then there are times when they aren’t.
“Little children, keep yourselves from idols. Amen.” 1 John 5:21 (NKJV)
I find it very interesting that John ends his letter by warning them against idols. The world these believers lived in was filled with idolatry. The Greeks and Romans had a multitude of gods that they worshiped. Rome also had institutionalized worship of the emperor. At least once a year every Roman citizen was required to worship the emperor by offering a pinch of incense and saying “Caesar is Lord.” Those who would not do this were considered to be traitors and a threat to national security. Knowing the great temptation of idolatry, John said they must keep themselves from idols.
Idolatry is something that has always pulled at people. Even the people of God in the Old Testament were frequently drawn away into idolatry. The great Dutch Theologian James Arminius said that, “…the human mind is both inclined and fitted to [think out in detail, devise] and invent excuses, nay even justifications, for sins, particularly for the sin of idolatry…” 
This is because humans are hard wired to worship something. If we don’t worship the true God, then we will find something or someone else to worship. Worshipping something other than the true God prevents us from knowing the true God. This is why John told his readers to keep themselves from idols.
Since idolatry is such a threat to our ability to know God, we must understand idolatry so we can keep ourselves from it. The essence of idolatry is to worship something other than God as it were God. It is to make something other than God ultimate in our lives. There are three forms of idolatry that we need to be aware of. I will talk about one today and the others the rest of the week.
What I’m calling metal idolatry is what we normally think of in regards to idolatry. It is the idolatry seen in the Old Testament as people bowed to and worshipped images of Baal and Moloch. It is the idolatry seen in Rome as the people prayed to and offered sacrifices to Zeus. It is the same sort of idolatry seen in India where people worship Vishnu and the other gods of Hinduism.
We often think that this sort of idolatry is confined somewhere in the past but it’s just about as common today as it was in the New Testament We just don’t see it as much here in America. While this form of idolatry will keep people from God, it’s not that much of a danger for us. This is why I’m not spending as much time on it as I will the other two.
For further study read Jeremiah 10. What does God say about idolatry in this passage? What does God say about the idols in this passage? What effect does idolatry have on those who are caught in idolatry?
 James (1560-1609) Arminius, Complete Works of Arminius, Under: “DISPUTATION 23”.